Nothing works properly after 10.5.2 update

I have a huge problem with my MacBook. After installing the 10.5.2 update and the graphics update, my MacBook ran for several hours without any issues (i left it working and was not doing anything on it). When I came back, I noticed that it ran unusually slow and tried to reboot it. It did not work - the blue screen appeared and then I was automatically logged back to Mac OS X. I had to hold the power button to shut it down, but to no avail - when it booted back, I noticed several problems:

I could not start any program - it just bounced on the dock and then disappeared;
There were no icons on the right side of the menubar - no clock, no spotlight - nothing;
I managed to copy the full 10.5.2 update from a USB stick, but it could not start - just as any other program;
When I tried to shut down, logout or restart, it took me to a blank blue screen and then automatically logged back in;
When I tried to run the system from the Mac OS X installation CD at startup, or do anything else at startup, no key combination seemed to work - C, shift, D. Nothing. So I cannot even Archive and Install, since it cannot boot from the CD.
The fan keeps spinning like crazy, the hard drive is active all the time, but nothing visible happens. The system is incredibly slow.

Try launching from the Install Disk that came with your computer, not the leopard CD the grey one, by holding down c when you start it up. Skip the install by going to utilities at the top, and do a verify and repair permissions. then when you go to restart and it ask which start up disk you want, choose the FOLDER that says OS X, it shouldn't be your HD icon. That may help your problems.

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